<!DOCTYPE html>
<html lang="zh-CN">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        let i
        let money = 200
        while (true) {
            i = +prompt(`
            1.存钱
            2.取钱
            3.查看余额
            4.退出`)
            if (i === 4) {
                break
            }
            switch (i) {
                case 1: let a = +prompt(`存多少钱`)
                    break
                case 2: let = +prompt(`取多少钱`)
            }
        }


    </script>
</body>

</html>